Studies in the selective synthesis of bidentate resorcinarene ligands

Kleinhans, Dewald Johannes (2010-03)

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010.

Thesis

ENGLISH ABSTRACT: Resorcinarenes are macrocyclic products formed from the condensation of aldehydes (aliphatic or aromatic) and resorcinol and have been used in a wide range of applications since their first synthesis. Applications include: HPLC stationary phases for the separation of pyrimidine bases, racemic drugs and isomers, the selective extractions of lanthanides and actinides, as molecular receptors, catalysis, NMR chiral shift agents, GC separations and as starting materials for the synthesis of macrocyclic compounds (e.g. cavitands and carcerands) to name but a few. The use of resorcinarenes in catalysis is still quite new and unexplored, while catalysis using calix[4]arenes, a related macrocycle, has been widely studied. In this thesis it was attempted to synthesise a C2v symmetric resorcinarene precursor that could be further functionalised to form distal bidentate ligands for coordination to transition metals. These compounds would then ultimately be used in catalytic testing, especially for Pd catalysed C-C bond formation. A dibromo resorcinarene precursor was synthesised starting from resorcinarene, using methodology developed by Shivanyuk. This molecule was functionalised with a small range of different electrophiles using lithium halogen exchange methodology, although low yields were returned for the expected distal resorcinarene compounds. Other methods of functionalisation of the resorcinarene, using an anionic ortho-Fries rearrangement and the reduction of a dinitrile resorcinarene to amine and aldehyde functionalities proved unsuccessful. Using a dithioether resorcinarene a di-nuclear coordination compound was formed with Pd(II). This compound was tested for catalytic activity with a Heck reaction, showing low yields for the coupling of styrene with bromobenzene.

AFRIKAANSE OPSOMMING: Resorsinarene is makrosikliese produkte wat gevorm word deur die kondensasie van aldehiede (alifaties of aromaties) met resorsinol en word in ‘n verskeidenheid van toepassings gebruik sedert hulle eerste sintese. Tipiese voorbeelde sluit in: stationêre fases vir die HPLC-skeiding van pirimidien-basisse, rasemiese farmaseutiese middels en isomere, die selektiwe ekstraksie van lantaniede en aktiniede, molekulêre reseptore, katalise, chirale verskuiwingsreagense vir KMR spektrometrie, GC-skeidings en as uitgangverbindings vir die sintese van ander makrosikliese verbindings (bv. kavitande en karserande). Die gebruik van resorsinarene in katalise is ’n splinternuwe onontginde veld. In teenstelling hiermee is calix[4]areen, ’n verwante makrosikliese verbinding, baie meer bestudeer en vir katalise gebruik. Die doel van hierdie tesis was om ’n C2v simmetriese uitgangstof te sintetiseer wat verder gefunksionaliseer kan word om distale, bidentate ligande vir koordinasie met oorgangsmetale te lewer. Daar is beplan om die katalitiese eienskappe van die komplekse te toets, veral vir Pd-gekataliseerde C–C-koppelings reaksies. Deur gebruik te maak van ’n protokol wat deur Shivanyuk ontwikkel is, is ’n dibromo-resorsinareen gesintetiseer uit resorsinareen. Verskillende elektrofiele is in ’n litium-halogeen uitruilreaksie gebruik om ’n beperkte verskeidenheid nuwe ligande te sintetiseer wat verskillende funksionele groepe besit. Ongelukkig was die opbrengste aan distale ligande baie laag en ander metodes is dus ook ondersoek om die funksionalisering te bewerkstellig. ’n Anioniese orto-Fries herrangskikkingsreaksie en die reduksie van ’n dinitriel-resorsinareen om amien- en aldehiedfunksies te lewer, was ook onsuksesvol. Die reaksie tussen ‘n Pd(II) sout en ‘n ditioeter-gederivatiseerde resorsinareen het ‘n koordinasie verbinding met twee metaalkerne gelewer. Hierdie kompleks is deur middel van ‘n Heck-koppelingsreaksie vir katalitiese aktiwiteit getoets, maar het lae opbrengste gelewer in die koppeling van stireen en bromobenseen.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/4194
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